nfp: add support for NFP3800/NFP3803 PCIe devices

Enable binding the nfp driver to NFP3800 and NFP3803 devices.
The PCIE_SRAM offset is different for the NFP3800 device, which also
only supports a single explicit group.

Changes to Dirk's work:
* 48-bit dma addressing is not ready yet. Keep 40-bit dma addressing
for NFP3800.

Signed-off-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Fei Qin <fei.qin@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>